Feed distribution means for vacuum filters

ABSTRACT

A liquid feed distribution trough having an arcuate bottom is mounted horizontally along the upper edge of a rotary drum filter tank. Within the feed distribution trough, an elongated paddle wheel is rotatably mounted for distributing a liquid containing particulates evenly throughout the trough. The edge of the trough is provided with a curved overflow lip to permit the uniformly distributed feed to gravitationally flow from the trough into the tank. The particulates are subsequently separated from the liquid by the rotary drum filter.

United States Patent [191 Solum Jan. 1, 1974 1 FEED DISTRIBUTION MEANSFOR 1,627,882 5/1927 Berry 162/357 x VACUUM FILTERS 3,554,866 1/1971Wyhstla 162/321 Inventor: Dallas H. Solum, Salt Lake City,

Utah

Assignee: Envirotech Corporation, Salt Lake City, Utah Filed: Apr. 3,1972 Appl. No.: 240,438

US. Cl 210/404, 162/321, 162/342, 210/456 Int. Cl B01d 33/06 Field ofSearch 210/456, 402-405; 162/357, 321, 323, 342

References Cited UNITED STATES PATENTS 1/1936 Rauch 210/404 5/1952Robison, Jr 210/404 X Primary Examiner-Frank A. Spear, Jr. AssistantExaminer-T. A. Granger Attorney-Richard F. Bojanowski et a1.

[ 5 7] ABSTRACT A liquid feed distribution trough having an arcuatebottom is mounted horizontally along the upper edge of a rotary drumfilter tank.Within the feed distribution trough, an elongated paddlewheel is rotatably mounted for distributing a liquid: containingparticulates evenly throughout the trough. The edge of the trough isprovided with a curved overflow lip to permit the uniformly distributedfeed to gravitationally flow from the trough into the tank. Theparticulates are subsequently separated from the liquid by the rotarydrum filter.

1 Claim, 4 Drawing Figures FEED DISTRIBUTION MEANS FOR VACUUM FILTERSBACKGROUND OF THE INVENTION 1. Field This invention relates to animproved rotary drum filter and particularly to a feed distributionsystem adapted for use on a rotary filter.

2. State of the Art Rotary drum filters are well known in the filtrationart. Such filters comprise generally a liquid holding tank in which afilter drum is rotatably mounted about its axis. The outside surface ofthe drum is covered by a filter medium across which a pressuredifferential is applied. A liquid feed containing particulates andsuspendable solids is introduced into the tank whereupon the solids areseparated from the liquid and collected on the filter medium as a filtercake.

Typically, the feed is introduced into the main tank through an inletpipe located at or near the bottom of one end of the tank. As the feedis being introduced, some of the heavier solids therein tend to settleand collect at or near the inlet point. When this occurs, the cakeformed on the drum is heavier at one end or deposits in uneven layersacross the drums surface. This imbalance causes inefficient filtering asonly a part of the filter is being properly utilized. When severalsmaller and dispersed inlets are used to distribute the feed more evenlywithin the tank, some of the inlets eventually become totally orpartially blocked requiring that the filter be removed from service andthe in lets cleaned.

OBJECTS OF THE INVENTION It is a primary object of this'invention toprovide a means for uniformly distributing suspended solids in a liquidmaterial.

A further object is to provide a feed distribution means which uniformlydistributes and exposes feed materials to the face of a rotary drumfilter.

BRIEF DESCRIPTION OF THE DRAWINGS The feed. distribution systemhereinafter described may be more readily understood by referring to theaccompanying drawings which are offered by way of example only and notin limitation of the invention, the scope of which is defined by theappended claims. In the drawings:

FIG. 1 is 'a pictorial view of a feed distribution system mounted to thefront edge of apartially shown rotary drum filter;

FIG. 2 is a side elevation view partially in section of FIG. 1;

FIG. 3 is a top view of the feed distribution system shown in FIG. 1; p

FIG. 4 is a cross-sectional view taken along line 4-4 of F IG. 3.

DETAILED DESCRIPTION OF THE INVENTION As is partially shown in FIGS. 1and 2, a conventional rotary drum filter comprises a filter drum lrotatably mounted in a main tank 14 having a rising wall 15. Overlyingthe drum is a filter medium 12. A feed distribution system (FIGS. 1-4)includes an elongated feed distribution trough. designated generally by16, which is mounted to the rising edge 18 of the tank 14 and extendslongitudinally thereacross. Preferably, the trough is positionedoutwardly and beyond the end of the filter drums horizontal radius. Afeed storage or conditioning tank 20 containing a mixer 22 is positionedbehind the feed distribution trough 16. The feed tank and troughcommunicate with each other by means of a flexible conduit 26 leadingfrom the tank and into a downwardly extending duct 28 which opens intothe Paddles or vanes 44 are fixed to the shaft and extend radiallytherefrom to just clear. the inner surface of the troughs arcuate bottom46. The paddles are longitudi nally elongated and the combination of thepaddles and the shaft may be described as a paddle wheel or starwheel.The vanes are formed from any suitable metal, rubber or plastic materialand, if desired, may be coated with a protective coating to minimizecorrosion.

A drive means 45 is provided to rotatably drive the shaft and, in turn,rotate the paddles which evenly distributes the feed throughout thelength of the trough. In addition, the rotating paddles assist intransporting solids in a uniform manner longitudinally over the lip sothat the solids may flow gravitationally downwardly along the risingwall 15 of the filter tank. A drain outlet is provided to selectivelyempty the contents of the trough for cleaning or other purposes.

Means may also be provided for varying the rotational speed of thepaddles. This feature permits a change in rotational speed if theconcentration and/or composition of the feed should vary.

In operation the feed material is continuously fed into the feeddistribution trough 16 from tank 20. The

paddles 40 are rotated and the feed entering the trough is evenlydistributed throughout the troughs length. When the trough becomesfilled, a continuous flow of homogenous feed overflows from the troughinto the main tank. Subsequent thereto, the solids are separated fromthe liquid in the tank by applying a vacuum to the undersurface of thefilter drum.

Although the inventive system hereinbefore described has particularapplication to rotary vaccum drum filters, the system can also beapplied to other types of filters such as disc or horizontal filters. Itmay also be used on pressure filters or combination pressure and vacuumfilters.

I claim:

1. In a rotary drum vacuum filter of the type including a tank formedwith ends and sidewalls and having a filter drum journalled in said endsfor rotation in said tank, improved feed supply means comprising anelongated arcuate-bottomed trough extending along, adjacent to and abovethe top edge of one tank sidewall, one wall of said trough forming alower overflow edge, means for supplying feed liquid into said troughand means for effecting even flow of said liquid over said edge fordistribution along the length of said tank, said means comprising anelongated starwheel journalled for rotation in said trough, means fordriving said starwheel, and an elongated lip connected to said edgealong the length of the trough said: lip being formed to slopedownwardly from said edge to terminate in said tank at an elevationbelow said top edge of said one tank sidewall.

1. In a rotary drum vacuum filter of the type including a tank formedwith ends and sidewalls and having a filter drum journalled in said endsfor rotation in said tank, improved feed supply means comprising anelongated arcuate-bottomed trough extending along, adjacent to and abovethe top edge of one tank sidewall, one wall of said trough forming alower overflow edge, means for supplying feed liquid into said troughand means for effecting even flow of said liquid over said edge fordistribution along the length of said tank, said means comprising anelongated starwheel journalled for rotation in said trough, means fordriving said starwheel, and an elongated lip connected to said edgealong the length of the trough said lip being formed to slope downwardlyfrom said edge to terminate in said tank at an elevation below said topedge of said one tank sidewall.